Flexible medium access control (mac) for ad hoc deployed wireless networks

ABSTRACT

Systems and methods are disclosed that facilitate wireless communication using resource utilization messages (RUMs), in accordance with various aspects. A RUM may be generated for a first node, such as an access point or an access terminal, to indicate that a first predetermined threshold has been met or exceeded. The RUM may be weighted to indicate a degree to which a second predetermined threshold has been exceeded. The first and/or second predetermined thresholds may be associated with various parameters associated with the node, such as latency, throughput, data rate, spectral efficiency, carrier-to-interference ratio, interference-over-thermal level, etc. The RUM may then be transmitted to one or more other nodes to indicate a level of disadvantage experienced by the first node.

CLAIM OF PRIORITY UNDER 35 U.S.C. §120

The present application for patent is a Divisional of patent applicationSer. No. 12/354,538 entitled “FLEXIBLE MEDIUM ACCESS CONTROL (MAC) FORAD HOC DEPLOYED WIRELESS NETWORKS” filed Jan. 15, 2009, which is acontinuation of patent application Ser. No. 11/553,417 entitled“FLEXIBLE MEDIUM ACCESS CONTROL (MAC) FOR AD HOC DEPLOYED WIRELESSNETWORKS” filed Oct. 26, 2006, pending, which claims priority toProvisional Application No. 60/730,631, entitled “WEIGHTED FAIR SHARINGOF A WIRELESS CHANNEL USING RESOURCE UTILIZATION MASKS,” filed on Oct.26, 2005, and Provisional Application No. 60/730,727, entitled“INTERFERENCE MANAGEMENT USING RESOURCE UTILIZATION MASKS SENT ATCONSTANT POWER SPECTRAL DENSITY (PSD),” filed on Oct. 26, 2005, andassigned to the assignee hereof and hereby expressly incorporated byreference herein.

CROSS REFERENCE TO CO-PENDING APPLICATIONS

This application also contains subject matter related to (1) U.S. patentapplication having Attorney Docket 051185 and entitling “INTERFERENCEMANAGEMENT USING RESOURCE UTILIZATION MASKS SENT AT CONSTANT PSD,” (2)U.S. patent application having Attorney Docket 051161 and entitling“WEIGHTED FAIR SHARING OF A WIRELESS CHANNEL USING RESOURCE UTILIZATIONMASKS,” and (3) U.S. patent application having Attorney Docket 060755and entitling “USING RESOURCE UTILIZATION MESSAGES IN A MULTI-CARRIERMAC TO ACHIEVE FAIRNESS,” all of which are filed on the same date asthis application and are also incorporated herein by reference.

BACKGROUND

I. Field

The following description relates generally to wireless communications,and more particularly to reducing interference and improving throughputand channel quality in a wireless communication environment.

II. Background

Wireless communication systems have become a prevalent means by which amajority of people worldwide communicate. Wireless communication deviceshave become smaller and more powerful in order to meet consumer needsand to improve portability and convenience. The increase in processingpower in mobile devices such as cellular telephones has led to anincrease in demands on wireless network transmission systems. Suchsystems typically are not as easily updated as the cellular devices thatcommunicate there over. As mobile device capabilities expand, it can bedifficult to maintain an older wireless network system in a manner thatfacilitates fully exploiting new and improved wireless devicecapabilities.

A typical wireless communication network (e.g., employing frequency,time, and code division techniques) includes one or more base stationsthat provide a coverage area and one or more mobile (e.g., wireless)terminals that can transmit and receive data within the coverage area. Atypical base station can simultaneously transmit multiple data streamsfor broadcast, multicast, and/or unicast services, wherein a data streamis a stream of data that can be of independent reception interest to amobile terminal. A mobile terminal within the coverage area of that basestation can be interested in receiving one, more than one or all thedata streams carried by the composite stream. Likewise, a mobileterminal can transmit data to the base station or another mobileterminal. Such communication between base station and mobile terminal orbetween mobile terminals can be degraded due to channel variationsand/or interference power variations. Accordingly, a need in the artexists for systems and/or methodologies that facilitate reducinginterference and improving throughput in a wireless communicationenvironment.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

According to various aspects, the subject innovation relates to systemsand/or methods that provide unified technology for wide and localwireless communication networks in order to facilitate achievingbenefits associated with both cellular and Wi-Fi technologies whilemitigating drawbacks associated therewith. For instance, cellularnetworks may be arranged according to a planned deployment, which canincrease efficiency when designing or building a network, while Wi-Finetworks are typically deployed in a more convenient, ad hoc manner.Wi-Fi networks may additionally facilitate providing a symmetricalmedium access control (MAC) channel for access points and accessterminals, as well as backhaul support with in-band wireless capability,which are not provided by cellular systems.

The unified technologies described herein facilitate providing asymmetrical MAC and backhaul support with in-band wireless capability.Moreover, the subject innovation facilitates deploying the network in aflexible manner. The methods described in this invention allow theperformance to adapt according to the deployment, thus providing goodefficiency if the deployment is planned or semi-planned, and providingadequate robustness if the network is unplanned. That is, variousaspects described herein permit a network to be deployed using a planneddeployment, (e.g., as in a cellular deployment scenario), an ad hocdeployment (e.g., such as may be utilized for a Wi-Fi networkdeployment), or a combination of the two. Still furthermore, otheraspects relate to supporting nodes with varied transmission power levelsand achieving inter-cell fairness with regard to resource allocation,which aspects are not adequately supported by Wi-Fi or cellular systems.

For example, according to some aspects, weighted fair-sharing of awireless channel may be facilitated by joint scheduling of atransmission by both a transmitter and a receiver using a resourceutilization message (RUM), whereby a transmitter requests a set ofresources based on knowledge of availability in its neighborhood, and areceiver grants a subset of the requested channels based on knowledge ofavailability in its neighborhood. The transmitter learns of availabilitybased on listening to receivers in its vicinity and the receiver learnsof potential interference by listening to transmitters in its vicinity.According to related aspects, RUMs may be weighted to indicate not onlythat a node is disadvantaged (as a receiver of data transmissions due tothe interference it sees while receiving) and desires a collisionavoidance mode of transmission, but also the degree to which the node isdisadvantaged. A RUM-receiving node may utilize the fact that it hasreceived a RUM, as well as the weight thereof, to determine anappropriate response. As an example, such an advertisement of weightsenables collision avoidance in a fair manner. The invention describessuch a methodology.

According to other aspects, a RUM-rejection threshold (RRT) may beemployed to facilitate determining whether to respond to a received RUM.For instance, a metric may be calculated using various parameters and/orinformation comprised by the received RUM, and the metric may becompared to the RRT to determine whether the sending node's RUM warrantsa response. According to a related aspect, a RUM sending node mayindicate its degree of disadvantage by indicating a number of channelsfor which the RUM applies, such that the number of channels (in general,these could be resources, frequency sub-carriers and/or time slots) isindicative of the degree of disadvantage. If the degree of disadvantageis reduced in response to the RUM, then the number of channels for whichthe RUM is sent may be reduced for a subsequent RUM transmission. If thedegree of disadvantage is not reduced, then the number of channels forwhich the RUM applies may be increased for a subsequent RUMtransmission.

A RUM may be sent at a constant power spectral density (PSD), and areceiving node may employ the received power spectral density and/orreceived power of the RUM to estimate a radio frequency (RF) channelgain between itself and the RUM sending node to determine whether itwill cause interference at the sending node (e.g., above a predeterminedacceptable threshold level) if it transmits. Thus, there may besituations wherein a RUM receiving node is able to decode the RUM fromthe RUM sending node, but determines that it will not causeinterference. When a RUM-receiving determines that it should obey theRUM, it can do so by choosing to backoff from that resource completelyor by choosing to use a sufficiently reduced transmit power bring itsestimated potential interference level below the predeterminedacceptable threshold level. Thus, “hard” interference avoidance(complete backoff) and “soft” interference avoidance (power control) areboth supported in a unified manner. According to a related aspect, theRUM may be employed by the receiving node to determine a channel gainbetween the receiving node and the RUM-sending node in order tofacilitate a determination of whether or not to transmit based onestimated interference caused at the sending node.

According to an aspect, a method of wireless communication may comprisegenerating a resource utilization message (RUM) at a first node, saidRUM indicating that a first predetermined threshold has been met orexceeded, weighting the RUM with a value that indicates a degree towhich a second predetermined threshold has been met or exceeded, andtransmitting the weighted RUM to one or more second nodes.

Another aspect relates to an apparatus that facilitates wirelesscommunication, comprising a generating module that generates a resourceutilization message (RUM) at a first node, said RUM indicating that afirst predetermined threshold has been met or exceeded; a weightingmodule that weights the RUM with a value that indicates a degree towhich a second predetermined threshold has been met or exceeded; and atransmitting module that sends the weighted RUM to one or more secondnodes.

Another aspect relates to an apparatus for wireless communication,comprising: means for generating a resource utilization message (RUM) ata first node, said RUM indicating that a first predetermined thresholdhas been met or exceeded; means for weighting the RUM with a value thatindicates a degree to which a second predetermined threshold has beenmet or exceeded; and means for transmitting the weighted RUM to one ormore second nodes.

Yet another aspect relates to a machine-readable medium comprisinginstructions for wireless communication, wherein the instructions uponexecution cause the machine to: generate a resource utilization message(RUM) at a first node, said RUM indicating that a first predeterminedthreshold has been met or exceeded; weight the RUM with a value thatindicates a degree to which a second predetermined threshold has beenmet or exceeded; and send the weighted RUM to one or more second nodes.

A further aspect relates to a processor that facilitates wirelesscommunication, the processor being configured to: generate a resourceutilization message (RUM) at a first node, said RUM indicating that afirst predetermined threshold has been met or exceeded; weight the RUMwith a value that indicates a degree to which a second predeterminedthreshold has been met or exceeded; and send the weighted RUM to one ormore second nodes.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative aspects ofthe one or more aspects. These aspects are indicative, however, of but afew of the various ways in which the principles of various aspects maybe employed and the described aspects are intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication system with multiple basestations and multiple terminals, such as may be utilized in conjunctionwith one or more aspects.

FIG. 2 is an illustration of a methodology for performing weighted fairsharing of a wireless channel using resource utilization masks/messages(RUMs), in accordance with one or more aspects described herein.

FIG. 3 illustrates a sequence of request-grant events that canfacilitate resource allocation, in accordance with one or more aspectsdescribed herein.

FIG. 4 is an illustration of several topologies that facilitateunderstanding of request-grant schemes, in accordance with variousaspects.

FIG. 5 illustrates a methodology for managing interference by employinga resource utilization message (RUM) that is transmitted at a constantpower spectral density (PSD), in accordance with one or more aspectspresented herein.

FIG. 6 is an illustration of a methodology for generating TxRUMs andrequests to facilitate providing flexible medium access control (MAC) inan ad hoc deployed wireless network, in accordance with one or moreaspects.

FIG. 7 is an illustration of a methodology for generating a grant for arequest to transmit, in accordance with one or more aspects.

FIG. 8 is an illustration of a methodology for achieving fairness amongcontending nodes by adjusting a number of subcarriers used to transmit aRUM according to a level of disadvantage associated with a given node,in accordance with one or more aspects.

FIG. 9 is an illustration of an RxRUM transmission between two nodes ata constant power spectral density (PSD), in accordance with one or moreaspects.

FIG. 10 is an illustration of a methodology for employing a constant PSDfor RUM transmission to facilitate estimating an amount of interferencethat will be caused by a first node at a second node, in accordance withone or more aspects.

FIG. 11 illustrates a methodology for responding to interference controlpackets in a planned and/or ad hoc wireless communication environment,in accordance with various aspects.

FIG. 12 is an illustration of a methodology that for generating anRxRUM, in accordance with various aspects described above.

FIG. 13 is an illustration of a methodology for responding to one ormore received RxRUMs, in accordance with one or more aspects.

FIG. 14 is an illustration of a wireless network environment that can beemployed in conjunction with the various systems and methods describedherein.

FIG. 15 is an illustration of an apparatus that facilitates wirelessdata communication, in accordance with various aspects.

FIG. 16 is an illustration of an apparatus that facilitates wirelesscommunication using resource utilization messages (RUMs), in accordancewith one or more aspects.

FIG. 17 is an illustration of an apparatus that facilitates generating aresource utilization message (RUM) and weighting the RUM to indicate alevel of disadvantage, in accordance with various aspects.

FIG. 18 is an illustration of an apparatus that facilitates comparingrelative conditions at nodes in a wireless communication environment todetermine which nodes are most disadvantaged, in accordance with one ormore aspects.

DETAILED DESCRIPTION

Various aspects are now described with reference to the drawings,wherein like reference numerals are used to refer to like elementsthroughout. In the following description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of one or more aspects. It may be evident, however, thatsuch aspect(s) may be practiced without these specific details. In otherinstances, well-known structures and devices are shown in block diagramform in order to facilitate describing one or more aspects.

As used in this application, the terms “component,” “system,” and thelike are intended to refer to a computer-related entity, eitherhardware, software, software in execution, firmware, middle ware,microcode, and/or any combination thereof. For example, a component maybe, but is not limited to being, a process running on a processor, aprocessor, an object, an executable, a thread of execution, a program,and/or a computer. One or more components may reside within a processand/or thread of execution and a component may be localized on onecomputer and/or distributed between two or more computers. Also, thesecomponents can execute from various computer readable media havingvarious data structures stored thereon. The components may communicateby way of local and/or remote processes such as in accordance with asignal having one or more data packets (e.g., data from one componentinteracting with another component in a local system, distributedsystem, and/or across a network such as the Internet with other systemsby way of the signal). Additionally, components of systems describedherein may be rearranged and/or complemented by additional components inorder to facilitate achieving the various aspects, goals, advantages,etc., described with regard thereto, and are not limited to the preciseconfigurations set forth in a given figure, as will be appreciated byone skilled in the art.

Furthermore, various aspects are described herein in connection with asubscriber station. A subscriber station can also be called a system, asubscriber unit, mobile station, mobile, remote station, remoteterminal, access terminal, user terminal, user agent, a user device, oruser equipment. A subscriber station may be a cellular telephone, acordless telephone, a Session Initiation Protocol (SIP) phone, awireless local loop (WLL) station, a personal digital assistant (PDA), ahandheld device having wireless connection capability, or otherprocessing device connected to a wireless modem.

Moreover, various aspects or features described herein may beimplemented as a method, apparatus, or article of manufacture usingstandard programming and/or engineering techniques. The term “article ofmanufacture” as used herein is intended to encompass a computer programaccessible from any computer-readable device, carrier, or media. Forexample, computer-readable media can include but are not limited tomagnetic storage devices (e.g., hard disk, floppy disk, magnetic strips. . . ), optical disks (e.g., compact disk (CD), digital versatile disk(DVD) . . . ), smart cards, and flash memory devices (e.g., card, stick,key drive . . . ). Additionally, various storage media described hereincan represent one or more devices and/or other machine-readable mediafor storing information. The term “machine-readable medium” can include,without being limited to, wireless channels and various other mediacapable of storing, containing, and/or carrying instruction(s) and/ordata. It will be appreciated that the word “exemplary” is used herein tomean “serving as an example, instance, or illustration.” Any aspect ordesign described herein as “exemplary” is not necessarily to beconstrued as preferred or advantageous over other aspects or designs.

It will be understood that a “node,” as used herein, may be an accessterminal or an access point, and that each node may be a receiving nodeas well as a transmitting node. For example, each node may comprise atleast one receive antenna and associated receiver chain, as well as atleast one transmit antenna and associated transmit chain. Moreover, eachnode may comprise one or more processors to execute software code forperforming any and all of the methods and/or protocols described herein,as well as memory for storing data and/or computer-executableinstructions associated with the various methods and/or protocolsdescribed herein.

Referring now to FIG. 1, a wireless network communication system 100 isillustrated in accordance with various aspects presented herein. System100 can comprise a plurality of nodes, such as one or more base stations102 (e.g., cellular, Wi-Fi or ad hoc, . . . ) in one or more sectorsthat receive, transmit, repeat, etc., wireless communication signals toeach other and/or to one or more other nodes, such as access terminals104. Each base station 102 can comprise a transmitter chain and areceiver chain, each of which can in turn comprise a plurality ofcomponents associated with signal transmission and reception (e.g.,processors, modulators, multiplexers, demodulators, demultiplexers,antennas, etc.), as will be appreciated by one skilled in the art.Access terminals 104 can be, for example, cellular phones, smart phones,laptops, handheld communication devices, handheld computing devices,satellite radios, global positioning systems, PDAs, and/or any othersuitable device for communicating over a wireless network.

The following discussion is provided to facilitate understanding of thevarious systems and/or methodologies described herein. According tovarious aspects, node weights can be assigned (e.g., to transmittingand/or receiving nodes), where each node weight is a function of anumber of flows supported by the node. “Flow,” as used herein,represents a transmission coming into or out of a node. The total weightof the node can be determined by summing the weights of all flowspassing through the node. For example, Constant Bit Rate (CBR) flows canhave predetermined weights, data flows can have weights proportional totheir type (e.g., HTTP, FTP, . . . ), etc. Moreover, each node may beassigned a predetermined static weight that may be added to the flowweight of each node in order to provide extra priority to each node.Node weight may also be dynamic and reflect the current conditions ofthe flows that a node carries. For example, the weight may correspond tothe worst throughput of a flow being carried (received) at that node. Inessence, the weight represents the degree of disadvantage that the nodeis experiencing and is used in doing fair channel access amongst a setof interfering nodes contending for a common resource.

Request messages, grant messages, and data transmissions may be powercontrolled: however, a node may nonetheless experience excessiveinterference that causes its signal-to-interference noise (SINR) levelsto be unacceptable. In order to mitigate undesirably low SINR, resourceutilization messages (RUMs) may be utilized, which can be receiver-side(RxRUM) and/or transmitter-side (TxRUM). An RxRUM may be broadcast by areceiver when interference levels on the receiver's desired channelsexceed a predetermined threshold level. The RxRUM may contain a list ofgranted channels upon which the receiver desires reduced interference,as well as node weight information. Additionally, the RxRUM may betransmitted at a constant power spectral density (PSD) or at a constantpower. Nodes that decode the RxRUM (e.g., transmitters contending withthe receiver emitting the RxRUM, . . . ) can react to the RxRUM. Forinstance, nodes hearing the RxRUM can calculate their respective channelgains from the receiver (e.g., by measuring the received PSD and withknowledge of the constant PSD at which the RxRUM was sent) and canreduce their respective transmission power levels to mitigateinterference. RxRUM recipients may even choose to backoff completelyfrom the indicated channels on the RxRUM. In order to ensure thatinterference avoidance happens in a fair manner, that is, to ensure thatall nodes get a fair share of transmission opportunities, weights may beincluded in the RxRUM. The weight of a given node can be utilized tocalculate the fair share of resources for allocation to the node.According to an example, thresholds used for sending and/or reacting toa RUM can be determined based on the behavior of a system. For instance,in a pure collision avoidance type of system, a RUM can be sent forevery transmission, and any node hearing the RUM can react by nottransmitting on the associated channel.

If channel bit mask, indicating which channels the RUM applies for, isincluded in the RUM, then an additional dimension for collisionavoidance can be realized, which may be useful when a receiver needs toschedule a small amount of data over a part of the channel and does notwant a transmitter to completely back off from the entire channel. Thisaspect may provide finer granularity in the collision avoidancemechanism, which may be important for bursty traffic.

A TxRUM may be broadcast by a transmitter when the transmitter is unableto request adequate resources (e.g., where a transmitter hears one ormore RxRUMs that force it to backoff on most of the channels). The TxRUMmay be broadcast before the actual transmission, to inform neighboringreceivers of impending interference. The TxRUM can inform all receiverswithin the listening range that, based on the RxRUMs the transmitter hasheard, the transmitter believes it has the most valid claim tobandwidth. The TxRUM can carry information about the weight of thetransmitter node, which can be used by neighboring nodes to calculatetheir respective shares of resources. Additionally, the TxRUM may besent out at a PSD or transmit power that proportional to a power levelat which data is transmitted. It will be appreciated that the TxRUM neednot be transmitted at a constant (e.g., high) PSD since only potentiallyaffected nodes need to be made aware of transmitter's condition.

The RxRUM carries weight information that is intended to convey to alltransmitters within “listening” range (e.g., whether they send data tothe receiver or not) the degree to which the receiver has been starvedfor bandwidth due to interference from other transmissions. The weightmay represent a degree of disadvantage and may be larger when thereceiver has been more disadvantaged and smaller when lessdisadvantaged. As an example, if throughput is used to measure thedegree of disadvantage, then one possible relationship may berepresented as:

${{RxRum}\mspace{14mu} {Weight}} = {Q\left( \frac{R_{target}}{R_{actual}} \right)}$

where R_(target) represents the desired throughput, R_(actual) is theactual throughput being achieved, and Q(x) represents the quantizedvalue of x. When there is a single flow at the receiver, then R_(target)may represent the minimum desired throughput for that flow, andR_(actual) may represent the average throughput that has been achievedfor that flow. Note that higher value weights representing a greaterdegree of disadvantage is a matter of convention. In a similar manner, aconvention where higher value weights represent lower degree ofdisadvantage may be utilized as long as the weight resolution logic isappropriately modified. For example, one could use the ratio of actualthroughput to target throughput (the inverse of the example shown above)to calculate the weights.

When there are multiple flows at the receiver, with potentiallydifferent R_(target) values, then the receiver may choose to set theweight based on the most disadvantaged flow. For example:

${{RxRum}\mspace{14mu} {Weight}} = {Q\left( {\max_{j}\left( \frac{R_{target}^{j}}{R_{actual}^{j}} \right)} \right)}$

where j is the flow index at the receiver. Other options, such as basingthe weight on the sum of the flow throughput, may be performed as well.Note that the functional forms used for the weights in the abovedescription are purely for illustration. The weight may be calculated ina variety of different manners and using different metrics thanthroughputs. According to a related aspect, the receiver can determinewhether it has data outstanding from a sender (e.g., a transmitter).This is true if it has received a request, or if it has received a priorrequest that it has not granted. In this case, the receiver can send outan RxRUM when R_(actual) is below R_(target).

A TxRUM may carry a single bit of information conveying whether it ispresent or not. A transmitter may set the TxRUM bit by performing apredefined series of actions. For example, the transmitter can collectRxRUMs it has recently heard, including a RxRUM from its own receiver ifthe receiver has sent one. If the transmitter has not received anyRxRUMs, it may send a request to its receiver without sending a TxRUM.If the only RxRUM is from its own receiver, then the transmitter maysend a request and a TxRUM.

Alternatively, if the transmitter has received RxRUMs, including onefrom its own receiver, the transmitter may sort the RxRUMs based on theRxRUM weights. If the transmitter's own receiver has the highest weight,then the transmitter may send a TxRUM and a request. However, if thetransmitter's own receiver is not the highest weight, then thetransmitter need not send a request or a TxRUM. In the event that thetransmitter's own receiver is one of several RxRUMs, all at the highestweight, then the transmitter sends a TxRUM and request with probabilitydefined by: 1/(all RxRUMs at highest weight). According to anotheraspect, if the receiver has received RxRUMs that do not include one fromits own receiver, then the transmitter may not send a request. Note thatthe entire sequence of RxRUM processing described above can be appliedeven in the case without TxRUMs. In such a case, the logic is applied bya transmitter node to determine whether to send a request to itsreceiver or not and if so, for what channels.

Based on the requests and/or TxRUMs that a receiver hears, the receivermay decide to grant a given request. When a transmitter has not made arequest, the receiver need not send a grant. If the receiver has heardTxRUMs, but none from a transmitter that it is serving, then thereceiver does not send a grant. If the receiver hears a TxRUM only fromtransmitters that it is serving, then it may decide to make a grant. Ifthe receiver has heard TxRUMs from its own transmitter as well as from atransmitter that it is not serving, then two outcomes are possible. Forinstance, if a running average of the transmission rate is at leastR_(target), then the receiver does not grant (e.g., it forces itstransmitter to be quiet). Otherwise the receiver grants with probabilitydefined as 1.0/(sum TxRUMs heard). If the transmitter has been granted,the transmitter transmits a data frame that can be received by thereceiver. Upon a successful transmission, both transmitter and receiverupdate the average rate for the connection.

According to other aspects, scheduling actions can be programmed toimplement equal grade of service (EGOS) or other schemes for managingfairness and quality of service among multiple transmitters and/or flowsto a receiver. A scheduler uses its knowledge of the rates received byits partner nodes to decide which nodes to schedule. However, thescheduler can abide by the interference rules imposed by the mediumaccess channel over which it operates. Specifically, the scheduler canobey the RUMs that it hears from its neighbors. For instance, on aforward link, a scheduler at an access point (AP) may send requests toall access terminals (ATs) for which it has traffic, unless it isblocked by RxRUMs. The AP may receive grants back from one or more ofthese ATs. An AT may not send a grant if it is superseded by a competingTxRUM. The AP may then schedule the AT that has the highest priority,according to the scheduling algorithm, and may transmit.

On a reverse link, each AT that has traffic to send may request the AP.An AT will not send a request if it is blocked by a RxRUM. The APschedules the AT that has the highest priority, according to thescheduling algorithm, while abiding by any TxRUMs that it has heard in aprevious slot. The AP then sends a grant to the AT. Upon receiving agrant, the AT transmits.

FIG. 2 is an illustration of a methodology 200 for performing weightedfair sharing of a wireless channel using resource utilizationmasks/messages (RUMs), in accordance with one or more aspects describedherein. At 202, a determination may be made regarding a number ofchannels over which a node (e.g., an access point, an access terminal,etc.) would prefer to transmit. Such determination may be based on, forinstance, need associated with a given amount of data to be transmitted,interference experienced at the node, or any other suitable parameter(e.g., latency, data rate, spectral efficiency, etc.) At 204, one ormore channels may be selected to achieve the desired number of channels.Channel selection may be performed with a preference for availablechannels. For instance, channels that are known to have been availablein a preceding transmission period may be selected before channels thatwere occupied in the preceding transmission period. At 206, a requestfor the selected channel(s) may be transmitted. The request may comprisea bitmask of preferred channels over which a transmitter (e.g., atransmitting node, . . . ) intends to transmit data, and may be sentfrom the transmitter to a receiver (e.g., a receiving node, a cellphone, smartphone, wireless communication device, access point, . . . ).The request may be a request for a first plurality of channels that werenot blocked in a most recent time slot, a request for a second pluralityof channels if the first plurality of channels is insufficient for datatransmission, etc. The request message sent at 206 may additionally bepower-controlled to ensure a desired level of reliability at thereceiver.

According to other aspects, the determination of the number of channelsdesired for a given transmission may be a function of a weightassociated with the node, a function of weights associated with othernodes requesting channels, a function of a number of channels availablefor transmission, or any combination of the preceding factors. Forexample, a weight may be a function of a number of flows through thenode, a level of interference experienced at the node, etc. According toother features, channel selection may comprise partitioning channelsinto one or more sets, and may be based in part on a received resourceutilization message (RUM) that indicates that one or more channels in aset of channels is unavailable. The RUM may be evaluated to determinewhether a given channel is available (e.g., is not identified by theRUM). For example a determination may be made that a given channel isavailable if it is not listed in the RUM. Another example is that achannel is deemed available even if a RUM was received for that channel,but the advertised weight for that channel was lower than the weightadvertised in the RUM sent by the node's receiver.

FIG. 3 illustrates a sequence of request-grant events that canfacilitate resource allocation, in accordance with one or more aspectsdescribed herein. A first series of events 302 is depicted, comprising arequest that is sent from a transmitter to a receiver. Upon receivingthe request, the receiver can send a grant message to the transmitter,which grants all or a subset of channels requested by the transmitter.The transmitter may then transmit data over some or all of the grantedchannels.

According to a related aspect, a sequence of events 304 can comprise arequest that is sent from a transmitter to a receiver. The request caninclude a list of channels over which the transmitter would like totransmit data to the receiver. The receiver may then send a grantmessage to the transmitter, which indicates all or a subset of thedesired channels have been granted. The transmitter may then transmit apilot message to the receiver, upon receipt of which the receiver maytransmit rate information back to the transmitter, to facilitatemitigating an undesirably low SINR. Upon receipt of the rateinformation, the transmitter may proceed with data transmission over thegranted channels and at the indicated transmission rate.

According to a related aspect, a TxRUM may be broadcast by a transmitterwhen the transmitter is unable to request adequate resources (e.g.,where a transmitter hears one or more RxRUMs that occupy most of thetransmitter's available channels). Such a TxRUM may carry informationabout the weight of the transmitter node, which may be used byneighboring nodes to calculate their respective shares of resources.Additionally, the TxRUM may be sent out at a PSD proportional to a powerlevel at which data is transmitted. It will be appreciated that theTxRUM need not be transmitted at a constant (e.g., high) PSD since onlypotentially affected nodes need to be made aware of transmitter'scondition.

The sequence of events 302 and 304 may be performed in view of aplurality of constraints that may be enforced during a communicationevent. For example, the transmitter may request any channel(s) that havenot been blocked by a RxRUM in a previous time slot. The requestedchannels may be prioritized with a preference for a successful channelin a most recent transmission cycle. In the event that there areinsufficient channels, the transmitter may request additional channelsto obtain a fair share thereof by sending TxRUMs to announce thecontention for the additional channels. The fair share of channels canthen be determined according to the number and weights of contendingneighbors (e.g., nodes), in view of RxRUMs that have been heard.

The grant from the receiver may be a subset of the channels listed inthe request. The receiver can be endowed with authority to avoidchannels exhibiting high interference levels during a most recenttransmission. In the event that the granted channels are insufficient,the receiver may add channels (e.g., up to the transmitter's fair share)by sending one or more RxRUMs. The transmitter's fair share of channelscan be determined by, for instance, evaluating the number and weights ofneighboring nodes, in view of TxRUMs that have been heard (e.g.,received).

When transmitting, the transmitter may send data over the all or asubset of channels granted in the grant message. The transmitter mayreduce transmission power on some or all channels upon hearing an RxRUM.In the event that the transmitter hears a grant and multiple RxRUMs on asame channel, the transmitter may transmit with reciprocal probability.For instance, if one grant and three RxRUMs are heard for a singlechannel, then the transmitter may transmit with a probability of ⅓, etc.(e.g., the probability that the transmitter will employ the channel is⅓).

According to other aspects, excess bandwidth may be allocated accordingto a sharing scheme that is unfettered with regard to the aboveconstraints. For instance, weight-based scheduling, as described above,can facilitate weighted fair sharing of resources. However, in a casewhere excess bandwidth is present, allocation of resources (e.g., abovethe minimum fair share), need not be constrained. For instance, ascenario may be considered wherein two nodes with full buffers each haveweights of 100 (e.g., corresponding to flow rates of 100 kbps), and aresharing a channel. In this situation, the nodes can share the channelequally. If they experience varying channel qualities, each of the twonodes may be granted, for example, 300 kbps. However, it may bedesirable to give only 200 kbps to node 1, in order to increase node 2'sshare to 500 kbps. That is, in such situations, it may be desirable toshare any excess bandwidth in some unfair fashion, in order to achievegreater sector throughput. The weighting mechanism may be extended in asimple manner to facilitate unfair sharing. For instance, in addition tothe weight, each node may also have a notion of its assigned rate, whichinformation can be associated with a service purchased by an AT. A nodemay continually update its average rate (over some suitable interval)and can send out RUMs when its average throughput is below the assignedrate to ensure that nodes will not vie for the excess resources beyondtheir assigned rate, which can then be apportioned in other sharingschemes.

FIG. 4 is an illustration of several topologies that facilitateunderstanding of request-grant schemes, in accordance with variousaspects. The first topology 402 has three links (A-B, C-D, E-F) in closeproximity, where every node A-F can hear the RUM from every other node.The second topology 404 has three links in a chain, and the middle link(C-D) interferes with both outer links (A-B and E-F), while the outerlinks do not interfere with each other. The RUMs may be simulated,according to this example, such that the range of a RUM is two nodes.The third topology 406 comprises three links on the right hand side(C-D, E-F, and G-H) that interfere with each other and can hear eachother's RUMs. The single link (A-B) on the left side only interfereswith the link (C-D).

According to various examples, for the topologies described above,performance of three systems is described in Table 1, below. In a “FullInformation” scenario, the availability of a RxRUM with bitmask andweights, as well as a TxRUM with bitmask and weights, is assumed. In the“Partial Information” scenario, RxRUM with bitmask and weights, andTxRUM with weights but no bitmasks, are assumed. Finally, in the “RxRUMAlone” scenario, no TxRUMs are sent out.

TABLE 1 Full Info Partial Info (RxRUM + (RxRUM + TxRUM bitmask) TxRUMweight) RxRUM alone Topology 1 Conv: 4.6 cycles Conv: 9.1 cycles Conv:10.3 cycles AB = 0.33 AB = 0.328 AB = 0.33 CD = 0.33 CD = 0.329 CD =0.33 EF = 0.33 EF = 0.325 EF = 0.33 Topology 2 Conv: 3.8 cycles Conv:5.4 cycles Conv: never AB = 0.5 AB = 0.5 AB = 0.62 CD = 0.5 CD = 0.5 CD= 0.36 EF = 0.5 EF = 0.5 EF = 0.51 Topology 3 Conv: 5.5 cycles Conv: 9.3cycles Conv: never AB = 0.67 AB = 0.665 AB = 0.77 CD = 0.33 CD = 0.33 CD= 0.21 EF = 0.33 EF = 0.33 EF = 0.31 GH = 0.33 GH = 0.33 GH = 0.31

As seen from Table 1, the Partial Info proposal is able to achieve fairshare of the weights at a small delay in convergence. The convergencenumbers show the number of cycles it takes for the schemes to convergeto a stable apportioning of the available channels. Subsequently, thenodes may continue to utilize the same channels.

FIG. 5 is an illustration of a methodology 500 for managing interferenceby employing a resource utilization message (RUM) that is transmitted ata constant power spectral density (PSD), in accordance with one or moreaspects presented herein. Request messages, grant messages, andtransmissions may be power controlled: however, a node may nonethelessexperience excessive interference that causes its signal-to-interferencenoise ratio (SINR) levels to be unacceptable. In order to mitigateundesirably low SINR, RUMs may be utilized, which can be receiver-side(RxRUM) and/or transmitter-side (TxRUM). A RxRUM may be broadcast by areceiver when interference levels on the receiver's desired channelsexceed a predetermined threshold level. The RxRUM may contain a list ofchannels upon which the receiver desires reduced interference, as wellas node weight information. Additionally, the RxRUM may be transmittedat a constant power spectral density (PSD). Nodes that “hear” the RxRUM(e.g., transmitters contending with the receiver emitting the RxRUM,)may react to the RxRUM, by stopping their transmission, or by reducingthe transmitted power.

For example, in ad hoc deployment of wireless nodes, acarrier-to-interference ratio (C/I) may be undesirably low at somenodes, which can hinder successful transmission. It will be appreciatedthat interference levels employed to calculate C/I may comprise noise,such that C/I may similarly be expressed as C/(I+N), where N is noise.In such cases, a receiver may manage interference by requesting thatother nodes in the vicinity either reduce their respective transmissionpowers or backoff completely from the indicated channels. At 502, anindication of channels (e.g., in a multi-channel system) that exhibit aC/I that is below a first predetermined threshold may be generated. At504, a message may be transmitted, the message comprising informationindicative of which channels exhibit inadequate C/Is. For example, afirst node (e.g., a receiver) may broadcast a RUM, along with a bitmaskcomprising information indicative of channels having C/Is that areundesirably low. The RUM may additionally be sent at a constant PSD thatis known to all nodes in the network. In this manner, nodes with varyingpower levels may broadcast with the same PSD.

The message (e.g., RUM) may be received by other nodes, at 506. Uponreceipt of the RUM, a second node (e.g., a transmitter) may utilize thePSD associated with the RUM to calculate the radio frequency (RF)distance (e.g. channel gain) between itself and the first node, at 508.The reaction of a given node to the RUM may vary according to the RFdistance. For instance, a comparison of the RF distance to a secondpredetermined threshold may be performed at 510. If the RF distance isbelow the second predetermined threshold (e.g., the first node and thesecond node are close to each other), then the second node can cease anyfurther transmissions over channels indicated in the RUM in order tomitigate interference, at 512. Alternatively, if the second node and thefirst node are sufficiently distant from each other (e.g., the RFdistance between them is equal to or greater than the secondpredetermined threshold when compared at 510), then the second node canutilize the RF distance information to predict a magnitude ofinterference that will be caused at the first node and that isattributable to the second node if the second node were to continue totransmit over channels indicated in the RUM, at 514. At 516, thepredicted interference level may be compared to a third predeterminedthreshold level.

For example, the third predetermined threshold may be a fixed portion ofa target interference-over-thermal (10T) level, which is the ratio ofinterference noise to thermal noise power measured over a commonbandwidth (e.g., approximately 25% of a target IOT of 6 dB, or someother threshold level). If the predicted interference is below thethreshold level, then the second node may continue transmitting over thechannels indicated in the RUM, at 520. If, however, the predictedinterference is determined to be equal to or greater than the thirdpredetermined threshold level, then at 518, the second node may reduceits transmission power level until the predicted interference is belowthe third threshold level. In this manner, a single message, or RUM, maybe employed to indicate interference over multiple channels. By causinginterference nodes to reduce power, affected nodes (e.g., receivers,access terminals, access points, . . . ) may receive bits successfullyover a subset of the multiple channels, and nodes that reduce theirtransmission power levels may also be permitted to continue theirrespective transmissions.

With regard to FIGS. 6 and 7, flexible medium access control may befacilitated by permitting a receiver to communicate to one or moretransmitters not only that it prefers a collision avoidance mode oftransmission, but also a measure of how disadvantaged it is relative toother receivers. In third generation cellular MACs, a need forinterference avoidance across cells may be mitigated by employing aplanned deployment scheme. Cellular MACs generally achieve high spatialefficiency (bits/unit area), but planned deployment is expensive, timeconsuming and may not be well suited for hotspot deployments.Conversely, WLAN systems such as those based on the 802.11 family ofstandards place very few restrictions on deployment, but cost and timesavings associated with deploying WLAN systems relative to cellularsystems comes at the price of increased interference robustness to bebuilt into the MAC. For instance, 802.11 family uses a MAC that is basedon carrier sense multiple access (CSMA). CSMA, fundamentally, is a“listen-before-transmit” approach wherein a node intending to transmithas to first “listen” to the medium, determine that it is idle, and thenfollow a backoff protocol prior to transmission. A carrier sense MAC maylead to poor utilization, limited fairness control, and susceptibilityto hidden and exposed nodes. In order to overcome deficienciesassociated with both planned deployment cellular systems and withWi-Fi/WLAN systems, various aspects described with regard to FIGS. 6 and7 can employ synchronous control channel transmission (e.g. to sendrequests, grants, pilots etc), efficient use of RUMs (e.g., an RxRUM maybe sent by a receiver when it wants interfering transmitters to backoff,a TxRUM may sent by a transmitter to let its intended receiver andreceivers that it interferes with know of its intention to transmit,etc.), as well as improved control channel reliability through reuse(e.g., so that multiple RUMs may be decoded simultaneously at thereceiver), etc.

In accordance with some features, RxRUMs may be weighted with acoefficient that is indicative of the degree of disadvantage of thereceiver in serving its transmitters. An interfering transmitter maythen use both the fact that it heard an RxRUM and the value of theweight associated with the RxRUM to determine a next action. Accordingto an example, when a receiver receives a single flow, the receiver maysend RxRUM when

${\frac{RST}{R_{actual}} < T},$

where RST (RUM sending threshold) is the throughput target for the flow,R_(actual) is the actual achieved throughput calculated as a short-termmoving average (e.g., through a single-pole IIR filter, . . . ), and Tis a threshold against which the ratio is compared. If the receiver isunable to schedule its transmitter during a particular slot, the ratefor that slot may be assumed to be 0. Otherwise the achieved rate inthat slot is a sample that may be fed to the averaging filter. Thethreshold, T, can be set to unity so that whenever the actual throughputfalls below the target throughput, the weight is generated andtransmitted.

A transmitter can “hear” an RxRUM if it can decode the RxRUM message. Atransmitter may optionally ignore the RxRUM message if it estimates thatthe interference it will cause at the RxRUM sender is below a RUMrejection threshold (RRT). In the instant MAC design, Rx/Tx RUMs,requests and grants may be sent on a control channel which has a verylow reuse factor (e.g., ¼ or smaller) to ensure that interference impacton the control information is low. A transmitter may analyze the set ofRxRUMs that is has heard, and, if an RxRUM heard from its intendedreceiver is the highest-weight RxRUM, the transmitter may send a requestwith a TxRUM indicating to all receivers that can hear the transmitter,(e.g., including its own receiver), that it has won the “contention” andis entitled to use the channel. Other conditions for sending a TxRUM,handling of multiple RxRUMs of equal weight, handling of multipleTxRUMs, requests, etc., are described in greater detail with regard toFIGS. 6 and 7, below. Setting the RxRUM weight and the correspondingactions at the transmitter permits a deterministic resolution ofcontention, and thereby improved utilization of the shared medium andweighted fair sharing through the setting of the RST. In addition tosetting the RST, which controls the probability of RxRUMs being sentout, the setting of the RRT can facilitate controlling a degree to whichthe system operates in collision avoidance mode.

With regard to the RST, from a system efficiency perspective, the RSTmay be employed such that a collision avoidance protocol or asimultaneous transmission protocol may invoked based on analysis ofwhich protocol achieves a higher system throughput for a specific userconfiguration. From a peak-rate perspective or delay-intolerant service,users may be permitted to burst data at a rate higher than that whichmay be achieved using simultaneous transmissions at the expense ofsystem efficiency. Additionally, certain types of fixed rate trafficchannels (e.g., control channels) may require a specific throughput tobe achieved, and the RST may be set accordingly. Moreover, certain nodesmay have a higher traffic requirement due to aggregation of a largetraffic volume. This is particularly true if a wireless backhaul is usedin a tree-like architecture and a receiver is scheduling a node that isclose to the root of the tree.

One methodology to determine a fixed RST is to set the RST based on theforward link edge spectral efficiency achieved in planned cellularsystems. The cell edge spectral efficiency indicates the throughput thatan edge user may achieve in a cellular system when the BTS transmits toa given user, with the neighbors being on all the time. This is so inorder to ensure that throughput with simultaneous transmissions is noworse than cell edge throughput in a planned cellular system, which maybe utilized to trigger a transition into collision avoidance mode toimprove throughput (e.g., over that which may be achieved usingsimultaneous transmission mode). According to other features, RSTs maybe different for different users (e.g., users may subscribe to differentlevels of service associated with different RSTs, . . . )

FIG. 6 is an illustration of a methodology 600 for generating TxRUMs andrequests to facilitate providing flexible medium access control (MAC) inan ad hoc deployed wireless network, in accordance with one or moreaspects. The TxRUM may inform all receivers within the listening rangethat based on the RxRUMs a transmitter has heard, the transmitterbelieves it is the one most entitled to bandwidth. A TxRUM carries asingle bit of information indicating its presence, and a transmitter mayset the TxRUM bit in the following manner.

At 602, the transmitter may determine whether it has just heard (e.g.,within a predetermined monitoring period, . . . ) one or more RxRUMs,including an RxRUM from its own receiver (for example, suppose A iscommunicating with B and interferes with C and D, then A may hear RxRUMsfrom B, C and D, with B being its receiver), if it has sent one (i.e. ifB has sent one in the running example). As described herein, a “node”may be an access terminal or an access point, and may comprise both areceiver and a transmitter. The usage of terminology such as“transmitter” and “receiver” in this description should therefore beinterpreted as “when a node plays the role of transmitter” and “when anode plays the role of a receiver” respectively. If the transmitter hasnot received any RxRUMs, then at 604 it sends a request to its receiverwithout sending a TxRUM. If the transmitter has received at least oneRxRUM, then at 606 a determination may be made regarding whether anRXRUM has been received from the transmitter's own receiver (e.g., areceiver at the transmitter's node, . . . ). If not, then at 608, adecision may be made to refrain from transmitting a TxRUM and associatedrequest.

If the determination at 606 is positive, then at 610, a furtherdetermination may be made regarding whether the RxRUM received from thetransmitter's own receiver is the only RxRUM that has been heard. If so,then at 612, the transmitter may send a TxRUM and a request to transmit.If the transmitter has received multiple RxRUMs including the RxRUM fromits own receiver, then at 614, the transmitter may proceed to sort theRxRUMs based on weights associated therewith. At 616, a determinationmay be made regarding whether the RxRUM received from the transmitter'sown receiver has a highest weight (e.g., a greatest level ofdisadvantage) of all the received RxRUMs. If so, then at 618, thetransmitter may send both a TxRUM and a request to transmit. If thedetermination at 616 is negative, then at 620, the transmitter mayrefrain from transmitting the TxRUM as well as the request. In ascenario in which the transmitter receives an RxRUM from its ownreceiver as well as one or more other RxRUMs and all are of equalweight, then the transmitter may send a TxRUM and request withprobability 1/N, where N is the number of RxRUMs having the highestweight. In one aspect, the logic of FIG. 6 may be applied without anyTxRUMs, but rather only requests. That is, the RxRUMs control whether anode can send a request for a particular resource or not.

“Disadvantage,” as used herein, may be determined as a function of, forinstance, a ratio of a target value to an actual value for a given node.For example, when disadvantage is measured as a function of throughput,spectral efficiency, data rate, or some other parameter where highervalues are desirable, then when the node is disadvantaged, the actualvalue will be relatively lower than the target value. In such cases, aweighted value indicative of the level of disadvantage of the node maybe a function of the ratio of the target value to the actual value. Incases where the parameter based upon which disadvantage is based isdesired to be low (e.g., latency,), a reciprocal of the ratio of thetarget value to the actual value may be utilized to generate the weight.As used herein, a node that is described as having a “better” conditionrelative to another node may be understood to have a lesser level ofdisadvantage (e.g., the node with the better condition has lessinterference, less latency, a higher data rate, higher throughput,higher spectral efficiency, etc., than another node to which it iscompared).

According to an example, transmitter A and transmitter C may transmitsimultaneously (e.g., according to a synchronous media access controlscheme wherein transmitters transmit at specified times and receiverstransmit at other specified times), to receiver B and receiver D,respectively. Receiver B may determine and/or have predetermined anamount of interference that it is experiencing, and may send an RxRUM totransmitters such as transmitter A and transmitter C. Receiver D neednot listen to the RxRUM, as receiver D transmits at the same time asreceiver B. To further the example, upon hearing the RxRUM from receiverB, transmitter C may evaluate receiver B's condition as indicated in theRxRUM, and may compare its own condition (which may be known to C oradvertised by the RxRUM sent by D) to that of receiver B. Upon thecomparison, several actions may be taken by transmitter C.

For instance, upon a determination that transmitter C is experiencing alower degree of interference than receiver B, transmitter C may back offby refraining from transmitting a request to transmit. Additionally oralternatively, transmitter C may evaluate or determine how muchinterference it is causing at receiver B (e.g., in a case where RxRUMsfrom receivers are sent at a same, or constant, power spectral density.Such a determination may comprise estimating a channel gain to receiverB, selecting a transmit power level, and determining whether a level ofinterference that would be caused at receiver B by a transmission fromtransmitter C at the selected transmit power level exceeds apredetermined acceptable threshold interference level. Based on thedetermination, transmitter C may opt to transmit at a power level thatis equal to a previous transmit power level or less.

In the event that transmitter C's condition (e.g., a level ofdisadvantage with regard to scarcity of resources, interference, . . . )is substantially equal to that of receiver B, transmitter C may evaluateand/or address weights associated with RxRUMs it has heard. Forinstance, if transmitter C has heard four RUMs having weights of, 3, 5,5, and 5, and the RxRUM heard from receiver B bears one of the weightsof 5 (e.g., has a weight equal to the heaviest weight of all RxRUMsheard by transmitter C), then C would send a request with probability ⅓.

FIG. 7 illustrates a methodology 700 for generating a grant for arequest to transmit, in accordance with one or more aspects. At 702, areceiver may assess requests and TxRUMs that it has recently heard orreceived (e.g., during a predefined monitoring period, . . . ). If norequests have been received, then at 704 the receiver may refrain fromsending a grant message. If at least one request and TxRUM has beenreceived, then at 706 a determination may be made regarding whether thereceived TxRUM(s) is/are from a transmitter that the receiver serves. Ifnot, then at 708, the receiver may refrain from sending a grant. If so,then at 710, the receiver may determine whether all received TxRUMs arefrom transmitters served by the receiver.

If the determination at 710 is positive, then a grant may be generatedand sent to one or more requesting transmitters, at 712. If thedetermination at 710 is negative and the receiver has received a TXRUMfrom its own transmitter in addition to a TxRUM from a transmitter thatthe receiver does not serve, then at 714, a determination may be maderegarding whether a running average of the transmission rate is greaterthan or equal to R_(target). If the running average of the transmissionrate is greater than or equal to R_(target), then at 716, the receivermay refrain from granting the requested resources. If not, then at 718,the receiver may send a grant with a probability of 1/N, where N is anumber of TxRUMs received. In another aspect, TxRUMs may include weightsjust as in RxRUMs and when multiple TxRUMs are heard, at least one fromone of its transmitters and one from another transmitter, then grantsare made based on whether the TxRUM with the highest weight was sent byone of its transmitters or not. In the event of a tie with multipleTxRUMs at highest weight, including one that came from one of itstransmitters, a grant is sent with probability m/N, where N is thenumber of TxRUMs heard at highest weight, m of which came from thereceiver's transmitters.

According to related aspects, the receiver may periodically and/orcontinuously assess whether it has data outstanding from a sender. Thisis true if the receiver has received a current request or if it hasreceived a prior request that it has not granted. In either case, thereceiver may send out an RxRUM whenever the average transmission rate isbelow R_(target). Additionally, upon a grant of a transmitter's request,the transmitter may transmit a data frame, which may be received by thereceiver. If there is data outstanding for the transmitter-receiverpair, then both the transmitter and the receiver may update the averagerate information for the connection.

FIG. 8 is an illustration of a methodology 800 for achieving fairnessamong contending nodes by adjusting a number of channels for which totransmit a RUM according to a level of disadvantage associated with agiven node, in accordance with one or more aspects. As described abovewith regard to preceding figures, an RxRUM is sent out to indicate thata receiver that it is experiencing poor communication conditions andwants a reduction in the interference it faces. The RxRUM includes aweight, which quantifies the degree of disadvantage that the node isexperiencing. According to an aspect, the weight may be set equal toRST/average throughput. Here, RST is the average throughput that thenode desires. When a transmitting node hears multiple RxRUMs, it mayutilize respective weights to resolve the contention between them. Ifthe RxRUM with the highest weight originated from the transmitter's ownreceiver, then it may decide to transmit. If not, the transmitter mayrefrain from transmitting.

A TxRUM is sent out by the transmitter to announce an impendingtransmission, and has two purposes. First, the TxRUM lets a receiverknow that its RxRUM won the local contention, so it may go schedule atransmission. Second, the TxRUM informs other neighboring receivers ofimpending interference. When a system supports multiple channels, theRUMs may carry a bitmask in addition to the weight. The bitmaskindicates the channels on which this RUM is applicable.

The RxRUM allows a node to clear interference in its immediateneighborhood, since nodes that receive the RxRUM may be induced torefrain from transmitting. While weights allow for a fair contention(e.g., a node with the greatest disadvantage wins), having amulti-channel MAC may provide another degree of freedom. The number ofchannels for which a node may send RxRUMs may be based on its degree ofdisadvantage to nodes with very poor history to catch up more rapidly.When the RxRUMs are successful and the transmission rate received by thenode in response thereto improves its condition, the node may reduce thenumber of channels for which it sends RxRUMs. If, due to heavycongestion, the RUMs do not succeed initially and throughput does notimprove, the node may increase the number of channels for which it sendsRUMs. In a very congested situation, a node may become highlydisadvantaged and may send RxRUMs for all channels, thereby degeneratingto the single carrier case.

According to the method, at 802, a level of disadvantage may bedetermined for a node and a RUM may be generated to indicate the levelof disadvantage to other nodes within listening range. For example, thelevel of disadvantage may be determined as a function of a level ofreceived service at the node, which may be impacted by variousparameters, such as latency, IOT, C/I, throughput, data rate, spectralefficiency, etc. At 804, a number of channels for which to send the RUMmay be selected, which may be commensurate to the level of disadvantage(e.g., the greater the disadvantage, the greater the number ofchannels). The RUM may be transmitted for the channels at 806. A qualityof service (QoS) may be measured for the node and disadvantage may bereassessed to determine whether the node's condition has improved, at808. Based on the measured QoS, the number of channels for which asubsequent RUM is transmitted may be adjusted, at 810. For instance, ifthe node's QoS did not improve or worsened, then the number of channelsfor which a subsequent RUM is transmitted may be increased at 810 toimprove the level of service received at the node. If the node's QoS hasimproved, then at 810 the number of channels for which a subsequent RUMis transmitted may be reduced to conserve resources. The method mayrevert to 806 for further iterations of RUM transmission, serviceevaluation, and channel number adjustment. The decision on whether toincrease or decrease the number of channels for which the RUM is sentmay also be a function of the QoS metric being used by the node. Forexample, increasing the number of channels for which RUMs are sent(based on continued or worsening level of disadvantage) may make sensefor throughput/data rate type metrics, but may not be so for latencymetrics.

According to related aspects, node-based and/or traffic-based prioritymay be incorporated by allowing nodes with higher priority to commandeera greater number of channels than nodes of lower priority. For example,a disadvantaged video caller may receive eight channels at once, while asimilarly disadvantaged voice caller only receive two carriers. Amaximum number of channels that a node may obtain may also be limited.The upper limit may be determined by the type of traffic being carried(e.g., small voice packets typically do not need more than a fewchannels), the power class of the node (e.g., a weak transmitter may notspread its power over too large a bandwidth), the distance to thereceiver and the resultant receive PSD, etc. In this manner, method 800may further reduce interference and improve resource savings. Stillother aspects provide for employing a bitmask to indicate a number ofchannels allocated to the node. For instance, a 6-bit mask may beutilized to indicate that RUMs may be sent for up to six channels. Thenode may additionally request that an interfering node refrain fromtransmitting over all or a subset of the allocated sub carriers.

FIG. 9 is an illustration of an RxRUM transmission between two nodes ata constant power spectral density (PSD), in accordance with one or moreaspects. When a node experiences heavy interference, it may benefit fromlimiting the interference caused by other nodes, which in turn permitsbetter spatial reuse and improved fairness. In the 802.11 family ofprotocols, request-to-send (RTS) and clear-to-send (CTS) packets areemployed to achieve fairness. Nodes that hear the RTS stop transmissionand permit the requesting node to successfully transmit the packet.However, often this mechanism results in a large number of nodes thatare turned off unnecessarily. Furthermore, nodes may send RTS and CTS atfull power over the entire bandwidth. If some nodes had higher powerthan others, then the range for RTS and CTS for different nodes could bedifferent. Thus, a low power node that may be interfered with stronglyby a high power node may be unable to shut off the high power nodethrough RTS/CTS, because the high power node would be out-of-range forthe low power node. In such a case, the high power node is a permanent“hidden” node to the low power node. Even if the low power node sends anRTS or a CTS to one of its transmitters or receivers, it will not beable to shut off the high power node. The 802.11 MAC, therefore,requires all nodes to have equal power. This introduces limitations inperformance, in particular from a coverage perspective.

The mechanism of FIG. 9 facilitates broadcasting a RUM from a receiverat a node that is experiencing an undesirably low SINR for one or morechannels. The RUM may be transmitted at a constant, known PSD,regardless of the transmit power capability of the node and a receivingnode may observe the received PSD and calculate a channel gain betweenitself and the RUM-transmitting node. Once the channel gain is known,the receiving node may determine an amount of interference that it islikely to cause (e.g., based in part on its own transmit power) at theRUM-transmitting node, and may decide whether or not to temporarilyrefrain from transmitting.

In cases where nodes in a network have different transmit powers, nodesthat hear the RUM may decide whether to shut down based on theirrespective known transmit powers and calculated channel gains. Thus, alow-power transmitter need not unnecessarily shut down since it will notcause significant interference. In this manner, onlyinterference-causing nodes may be shut down, thus mitigating theafore-mentioned deficiencies of conventional RTS-CTS mechanisms.

For example, a first node (Node A) may receive an RxRUM from a secondnode (Node B) over a channel, h. The RxRUM may be transmitted at a powerlevel, pRxRUM, and a received signal value, X, may be evaluated suchthat X is equal to the sum of the channel, h, multiplied by thetransmission power, pRxRUM, plus noise. Node A may then perform achannel estimation protocol to estimate h by dividing the receivedsignal value, X, by pRxRUM. If node B's weight higher than node A'sweight, then Node A may further estimate interference that a Node Atransmission may cause to Node B, by multiplying the channel estimate bya desired transmit power (p_(A)), such that:

I _(A) =h _(est) *p _(A)

where I_(A) is the interference caused by node A at node B.

According to an example, consider a system where maximum transmissionpower, M, is determined to be 2 Watts, and minimum transmissionbandwidth is 5 MHz, then a maximum PSD is 2 Watts/5 MHz, or 0.4 W/MHz.Suppose the minimum transmit power in the system is 200 mW. Then, theRUM is designed to have a range such that is equal to the range of themaximum allowed PSD in the system. This power spectral density for the200 mW transmitter and data rate for the RUM are then chosen to equalizethose ranges. It will be understood that the foregoing example ispresent for illustrative purposes and that the systems and/or methodsdescribed herein are not limited to the specific values presented above,but rather may utilize any suitable values.

FIG. 10 is an illustration of a methodology 1000 for employing aconstant PSD for RUM transmission to facilitate estimating an amount ofinterference that will be caused by a first node at a second node, inaccordance with one or more aspects. At 1002, a first node may receivean RxRUM, at a known PSD, from a second node. At 1004, the first nodemay calculate channel gain between itself and the second node based onthe known PSD. At 1006, the first node may employ a transmission PSDassociated with its own transmissions to estimate an amount ofinterference the first node may cause at the second node, based at leastin part on the channel gain calculated at 1004. The interferenceestimate may be compared to a predetermined threshold value, at 1008, todetermine whether the first node should transmit or refrain fromtransmitting. If the estimate is greater than the predeterminedthreshold, then the first node may refrain from transmitting (this couldinclude either transmitting data or transmitting a request), at 1012. Ifthe estimate is less than the predetermined threshold, then the firstnode may transmit, at 1010, because it does not substantially interferewith the second node. It will be appreciated that the RxRUM transmittedby the second node may be heard by multiple receiving nodes within agiven proximity to the second node, each of which may perform method1000 to evaluate whether not it should transmit.

According to another example, a second node may transmit at, forinstance, 200 milliwatts, and a first node may transmit at 2 Watts. Insuch a case, the second node may have a transmission radius of r, andthe first node may have a transmission radius of 10r. Thus, the firstnode may be positioned up to 10 times further away from the second nodethan the second node typically transmits or receives, but may still becapable of interfering with the second node because of its highertransmission power. In such a case, the second node may boost itstransmit PSD during RxRUM transmission to ensure that the first nodereceives the RxRUM. For example, the second node may transmit the RxRUMat a maximum allowable PSD, which may be predefined for a given network.The first node may then perform method 1000 and determine whether or notto transmit, as described above.

FIG. 11 illustrates a methodology 1100 for responding to interferencecontrol packets in a planned and/or ad hoc wireless communicationenvironment, in accordance with various aspects. At 1102, an RxRUM froma first node may be received at a second node. At 1104, a metric valuemay be generated based at least in part on predetermined valuesassociated with the RUM. For instance, when a RUM is received at 1102,the receiving node (e.g., the second node) knows or may determine theRUM_Rx_PSD by estimating the RUM received power, RUM_Tx_PSD (a knownconstant of the system), and Data_Tx_PSD (the PSD at which the RUMreceiving node would like to transmit its data). RUM_Tx_PSD andRUM_Rx_PSD are also quantified in dBm/Hz, where the former is a constantfor all nodes and the latter depends on channel gain. Similarly, Data_TxPSD is measured in dBm/Hz and may be dependent on the power classassociated with the node. The metric generated at 1104 may be expressedas:

metric=Data_(—) Tx_PSD+(RUM_(—) Rx_PSD−RUM_(—) Tx_PSD)

which represents an estimate of the possible interference that theRUM-transmitting node (e.g., for a TxRUM) or the RUM-receiving node(e.g., for an RxRUM) may cause at the other node.

At 1106, the metric value may be compared to a predetermined RUMrejection threshold (RRT) that is defined in dBm/Hz. If the metric isgreater than or equal to RRT, then the second node may respond to theRUM at 1108. If the metric is less than RRT, then the second node mayrefrain from responding to the node (e.g., because it will notsubstantially interfere with the first node)), at 1110. The response tothe RUM at 1108 may remove interference related to aninterference-over-thermal (10T) ratio that is greater than a predefinedvalue, Ω, which is measured in decibels, over thermal noise N₀, which ismeasured in dBm/Hz (e.g., such that the metric≧Ω+N₀). In order to assurethat all substantial potential interferers are silent, RRT may be setsuch that RRT=Ω+N₀. It is to be noted that the task of determining ifthe RRT threshold would be met or not is undertaken by the RxRUMreceiving node only when the advertised weight on the RUM indicates thatthe RUM sender has a greater degree of disadvantage than the RUMrecipient.

FIG. 12 is an illustration of a methodology 1200 that for generating anRxRUM, in accordance with various aspects described above. At 1202, aRUM may be generated at a first node, wherein the RUM comprisesinformation that indicates that a first predetermined threshold has beenmet or exceeded. The first predetermined threshold may represent, forinstance, a level of interference over thermal noise (10T), a data rate,a carrier-to-interference ratio (C/I), a level of throughput, a level ofspectral efficiency, a level of latency, or any other suitable measureby which a service at the first node may be measured. At 1204, the RUMmay be weighted in order to indicate a degree to which a secondpredetermined threshold has been exceeded. According to some aspects,the weight value may be a quantized value.

The second predetermined threshold may represent for instance, a levelof interference over thermal noise (10T), a data rate, acarrier-to-interference ratio (C/I), a level of throughput, a level ofspectral efficiency, a level of latency, or any other suitable measureby which a level of service at the first node may be measured. Althoughthe first and second predetermined thresholds may be substantiallyequal, they need not be. Additionally, the first and secondpredetermined thresholds may be associated with different parameters(e.g.: IOT and C/I, respectively; latency and data rate, respectively;or any other permutation of the described parameters). At 1206, theweighted RUM may be transmitted to one or more other nodes.

FIG. 13 is an illustration of a methodology 1300 for responding to oneor more received RxRUMs, in accordance with one or more aspects. At1302, an RxRUM may be received at a first node from a second (or more)node(s). The RxRUM may comprise information related to a condition ofthe second node (e.g., a level of disadvantage, as described above),which may be utilized by the first node at 1304 to determine thecondition of the second node. At 1306, the condition of the second nodemay be compared to the condition of the first node. The comparison maypermit a determination of whether to transmit data, at 1308.

For instance, if the comparison indicates that the condition of thefirst node is better than that of the second node, then the first nodemay refrain from sending data (e.g., to back off and permit the moredisadvantage second node to communicate more effectively). Additionallyor alternatively, if the condition of the first node is better than thatof the second node, the first node may proceed to determine a level ofinterference that the first node may cause at the second node, asdescribed above with regard to FIG. 10. Such a determination maycomprise, for instance, utilizing a known constant power or a knownconstant power spectral density at which the second node transmitted theRxRUM, estimating a channel gain between the first and second nodes,selecting a transmission power level for transmission from the firstnode to the second node, estimating a level of interference that atransmission at the selected power level would cause at the second node,and determining whether the estimated interference level exceeds apredetermined acceptable interference threshold level.

In the event that the comparison indicates that the first node'scondition is worse than the second node's condition, the first node mayselect to ignore the RUM. According to another aspect, in the event thatthe first node and the second node have substantially equal conditions,a weight-handling mechanism may be employed, as described above withregard to FIG. 6. According to still other aspects, informationcontained in the RUM may be utilized to generate a metric value that maybe compared to a RUM rejection threshold (RRT) to determine whether ornot to respond to the RUM, as described with regard to FIG. 11.According to still other aspects, upon a determination to transmit dataat 1308, such transmission may comprise sending communication data overa first channel, transmitting a request-to-send message over the firstchannel, and/or sending a request-to-send message over a second channel,which requests to send data over the first channel.

In another aspect, additional information may be included along with arequest to help a scheduler know the outcome of RxRUM processing at thenode. For example, suppose A transmits data to B and C to D. Suppose Band D both send out RxRUMs, but the weight used by B is higher (moredisadvantaged) than D. Then, A would send a request to B (since itprocessed the received RxRUMs and concluded that its receiver, viz. B,is most disadvantaged) and include a “Best” bit, indicating that it woncontention and should be scheduled expeditiously as it may not keepwinning in the future. By contrast, C would process the RUMs andconclude that it cannot request. However, it may let D know that eventhough it cannot be scheduled currently, it has data to send and Dshould persist in sending RxRUMs. For example, if D does not hear anyrequests, it may erroneously conclude that none of its transmitters haveany data to send and may stop sending RxRUMs. To prevent this, C sends a“request” with an indication that it is “blocked” by RxRUMs from others.This will serve as an indication to D to not schedule C currently, butkeep sending RxRUMs in the hope that C will win contention at somepoint.

FIG. 14 shows an exemplary wireless communication system 1400. Thewireless communication system 1400 depicts one base station and oneterminal for sake of brevity. However, it is to be appreciated that thesystem can include more than one base station and/or more than oneterminal, wherein additional base stations and/or terminals can besubstantially similar or different for the exemplary base station andterminal described below. In addition, it is to be appreciated that thebase station and/or the terminal can employ the methods (FIGS. 2, 5-8,and 10-13) and/or systems (FIGS. 1, 3, 4, 9, and 15-18) described hereinto facilitate wireless communication there between. For example, nodesin the system 1400 (e.g., base station and/or terminal) may store andexecute instructions for performing any of the above-described methods(e.g., generating RUMS, responding to RUMs, determining nodedisadvantage, selecting a number of subcarriers for RUM transmission, .. . ) as well as data associated with performing such actions and anyother suitable actions for performing the various protocols describedherein.

Referring now to FIG. 14, on a downlink, at access point 1405, atransmit (TX) data processor 1410 receives, formats, codes, interleaves,and modulates (or symbol maps) traffic data and provides modulationsymbols (“data symbols”). A symbol modulator 1415 receives and processesthe data symbols and pilot symbols and provides a stream of symbols. Asymbol modulator 1420 multiplexes data and pilot symbols and providesthem to a transmitter unit (TMTR) 1420. Each transmit symbol may be adata symbol, a pilot symbol, or a signal value of zero. The pilotsymbols may be sent continuously in each symbol period. The pilotsymbols can be frequency division multiplexed (FDM), orthogonalfrequency division multiplexed (OFDM), time division multiplexed (TDM),frequency division multiplexed (FDM), or code division multiplexed(CDM).

TMTR 1420 receives and converts the stream of symbols into one or moreanalog signals and further conditions (e.g., amplifies, filters, andfrequency upconverts) the analog signals to generate a downlink signalsuitable for transmission over the wireless channel. The downlink signalis then transmitted through an antenna 1425 to the terminals. Atterminal 1430, an antenna 1435 receives the downlink signal and providesa received signal to a receiver unit (RCVR) 1440. Receiver unit 1440conditions (e.g., filters, amplifies, and frequency downconverts) thereceived signal and digitizes the conditioned signal to obtain samples.A symbol demodulator 1445 demodulates and provides received pilotsymbols to a processor 1450 for channel estimation. Symbol demodulator1445 further receives a frequency response estimate for the downlinkfrom processor 1450, performs data demodulation on the received datasymbols to obtain data symbol estimates (which are estimates of thetransmitted data symbols), and provides the data symbol estimates to anRX data processor 1455, which demodulates (i.e., symbol demaps),deinterleaves, and decodes the data symbol estimates to recover thetransmitted traffic data. The processing by symbol demodulator 1445 andRX data processor 1455 is complementary to the processing by symbolmodulator 1415 and TX data processor 1410, respectively, at access point1405.

On the uplink, a TX data processor 1460 processes traffic data andprovides data symbols. A symbol modulator 1465 receives and multiplexesthe data symbols with pilot symbols, performs modulation, and provides astream of symbols. A transmitter unit 1470 then receives and processesthe stream of symbols to generate an uplink signal, which is transmittedby the antenna 1435 to the access point 1405.

At access point 1405, the uplink signal from terminal 1430 is receivedby the antenna 1425 and processed by a receiver unit 1475 to obtainsamples. A symbol demodulator 1480 then processes the samples andprovides received pilot symbols and data symbol estimates for theuplink. An RX data processor 1485 processes the data symbol estimates torecover the traffic data transmitted by terminal 1430. A processor 1490performs channel estimation for each active terminal transmitting on theuplink. Multiple terminals may transmit pilot concurrently on the uplinkon their respective assigned sets of pilot subbands, where the pilotsubband sets may be interlaced.

Processors 1490 and 1450 direct (e.g., control, coordinate, manage,etc.) operation at access point 1405 and terminal 1430, respectively.Respective processors 1490 and 1450 can be associated with memory units(not shown) that store program codes and data. Processors 1490 and 1450can also perform computations to derive frequency and impulse responseestimates for the uplink and downlink, respectively.

For a multiple-access system (e.g., FDMA, OFDMA, CDMA, TDMA, etc.),multiple terminals can transmit concurrently on the uplink. For such asystem, the pilot subbands may be shared among different terminals. Thechannel estimation techniques may be used in cases where the pilotsubbands for each terminal span the entire operating band (possiblyexcept for the band edges). Such a pilot subband structure would bedesirable to obtain frequency diversity for each terminal. Thetechniques described herein may be implemented by various means. Forexample, these techniques may be implemented in hardware, software, or acombination thereof. For a hardware implementation, the processing unitsused for channel estimation may be implemented within one or moreapplication specific integrated circuits (ASICs), digital signalprocessors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), field programmable gate arrays(FPGAs), processors, controllers, micro-controllers, microprocessors,other electronic units designed to perform the functions describedherein, or a combination thereof. With software, implementation can bethrough means (e.g., procedures, functions, and so on) that perform thefunctions described herein. The software codes may be stored in memoryunit and executed by the processors 1490 and 1450.

For a software implementation, the techniques described herein may beimplemented with modules/means (e.g., procedures, functions, and so on)that perform the functions described herein. The software codes may bestored in memory units and executed by processors. The memory unit maybe implemented within the processor or external to the processor, inwhich case it can be communicatively coupled to the processor viavarious means as is known in the art.

Now turning to FIGS. 15-18 and to the various modules described withregard thereto, it will be appreciated that a module for transmittingmay comprise, for example, a transmitter, and/or may be implemented in aprocessor, etc. Similarly, a module for receiving may comprise areceiver and/or may be implemented in a processor, etc. Additionally, amodule for comparing, determining, calculating, and/or performing otheranalytical actions, may comprise a processor that executes instructionsfor performing the various and respective actions.

FIG. 15 is an illustration of an apparatus 1500 that facilitateswireless data communication, in accordance with various aspects.Apparatus 1500 is represented as a series of interrelated functionalblocks, which can represent functions implemented by a processor,software, or combination thereof (e.g., firmware). For example,apparatus 1500 may provide modules for performing various acts such asare described above with regard to various figures. Apparatus 1500comprises a module for determining 1502 a number of channels desired fortransmission. The determination may be performed as a function of aweight associated with a node in which the apparatus is employed, aweight associated with one or more other nodes, a number of channelsavailable for transmission, etc. Additionally, each weight may be afunction of a number of flows supported by the node associated with theweight. Additionally or alternatively, a given weight may be a functionof interference experienced by the node.

Apparatus 1500 additionally comprise a module for selecting 1504 thatselects channels for which the node may transmit a request. Module forselecting 1504 additionally may evaluate a received resource utilizationmessage (RUM) to determine which channels are available and which arenot. For instance, each RUM may comprise information associated withunavailable channels, and the module for selecting 1054 may determinethat a given channel that is not indicated by the RUM is available. Amodule for sending 1506 may transmit a request for at least one channelselected by module for selecting 1504. It will be appreciated thatapparatus 1500 may be employed in an access point, an access terminal,etc., and may comprise any suitable functionality to carry out thevarious methods described herein.

FIG. 16 is an illustration of an apparatus 1600 that facilitateswireless communication using resource utilization messages (RUMs), inaccordance with one or more aspects. Apparatus 1600 is represented as aseries of interrelated functional blocks, which can represent functionsimplemented by a processor, software, or combination thereof (e.g.,firmware). For example, apparatus 1600 may provide modules forperforming various acts such as are described above with regard toprevious figures. Apparatus 1600 comprises a module for determining 1602that determines a level of disadvantage for a node, and a module forgenerating a RUM 1604 that generates a RUM if module for determining1602 determines that a level or received service at the node is at orbelow a predetermined threshold level. A module for selecting 1606 mayselect one or more resources for which to send the RUM, and module forgenerating the RUM 1604 may then indicate such channels in the RUM. Amodule for transmitting 1608 may then transmit the RUM.

Module for selecting resources 1606 may adjust a number of selectedresources for which subsequent a subsequent RUM is transmitted based ona determination by module for determining 1602 that the level ofreceived service has improved in response to a previous RUM. Forinstance, in such a scenario, module for selecting 1606 may reduce anumber of resources indicated in a subsequent RUM in response to animproved level of received service at the node, and may increase anumber of selected resources in response to a decreased or static levelof received service. According to other aspects, module for determining1602 may determine the level of received service at the node as afunction of one or more of interference-over-thermal noise, latency,data rate achieved at the node, spectral efficiency, throughput,carrier-to-interference ratio, or any other suitable parameter ofservice received at the node. It will be appreciated that apparatus 1600may be employed in an access point, an access terminal, etc., and maycomprise any suitable functionality to carry out the various methodsdescribed herein.

FIG. 17 is an illustration of an apparatus 1700 that facilitatesgenerating a resource utilization message (RUM) and weighting the RUM toindicate a level of disadvantage, in accordance with various aspects.Apparatus 1700 is represented as a series of interrelated functionalblocks, which can represent functions implemented by a processor,software, or combination thereof (e.g., firmware). For example,apparatus 1700 may provide modules for performing various acts such asare described above with regard to various figures described above.Apparatus 1700 comprises module for generating a RUM 1702, which maygenerate a RUM that indicates that a first predetermined threshold hasbeen exceeded. The first predetermined threshold may be associated withand/or represent a threshold level of interference over thermal noise(JOT), a data rate, a carrier-to-interference ratio (C/I), a level ofthroughput, a level of spectral efficiency, a level of latency, etc.

Apparatus 1700 may additionally comprise a module for weighting the RUM1704, which may weight the RUM with a value indicative of a degree towhich a second predetermined threshold has been exceeded, which maycomprise determining a ration of an actual value of a parameter (e.g.,interference over thermal noise (10T), a data rate, acarrier-to-interference ratio (C/I), a level of throughput, a level ofspectral efficiency, a level of latency, etc.) achieved at the node to atarget, or desired, value. Additionally, the weighted value may be aquantized value. It will be appreciated that apparatus 1700 may beemployed in an access point, an access terminal, etc., and may compriseany suitable functionality to carry out the various methods describedherein.

FIG. 18 is an illustration of an apparatus 1800 that facilitatescomparing relative conditions at nodes in a wireless communicationenvironment to determine which nodes are most disadvantaged, inaccordance with one or more aspects. Apparatus 1800 is represented as aseries of interrelated functional blocks, which can represent functionsimplemented by a processor, software, or combination thereof (e.g.,firmware). For example, apparatus 1800 may provide modules forperforming various acts such as are described above with regard tovarious figures. Apparatus 1800 may be employed in a first node andcomprises a module for receiving RUMs 1802 that receives RUMs from atleast one second node. Apparatus 1800 may additionally comprise a modulefor determining 1804 that determines a condition of the second nodebased on information associated with a RUM received from the secondnode, and a module for comparing 1806 that compares a condition of thefirst node to the determined condition of the second node. The modulefor determining 1804 may then further determine whether to transmit dataover a first channel based on the comparison.

According to various other aspects, the determination of whether totransmit may be based on whether the first node's condition is better,substantially equal to, or worse than the second node's condition.Additionally, the module for determining 1804 may transmit a data signalover the first channel, a request-to-send message over the firstchannel, or a request-to-send message over a second channel. In thelatter case, the request-to send message sent over the second channelmay comprise a request to transmit data over the first channel. It willbe appreciated that apparatus 1800 may be employed in an access point,an access terminal, etc., and may comprise any suitable functionality tocarry out the various methods described herein.

What has been described above includes examples of one or more aspects.It is, of course, not possible to describe every conceivable combinationof components or methodologies for purposes of describing theaforementioned aspects, but one of ordinary skill in the art mayrecognize that many further combinations and permutations of variousaspects are possible. Accordingly, the described aspects are intended toembrace all such alterations, modifications and variations that fallwithin the spirit and scope of the appended claims. Furthermore, to theextent that the term “includes” is used in either the detaileddescription or the claims, such term is intended to be inclusive in amanner similar to the term “comprising” as “comprising” is interpretedwhen employed as a transitional word in a claim.

1. A method of wireless communication, comprising: receiving at a firstnode a message indicating a desire to reduce interference at a secondnode, wherein the message specifies one or more resources on which thereduced interference is desired; and determining a transmission power onthe one or more resources based on the message.
 2. The method of claim1, wherein the transmission power is zero.
 3. The method of claim 1,wherein the one or more resources comprise at least one channel.
 4. Themethod of claim 1, wherein the one or more resources comprise one ormore sub-carriers.
 5. The method of claim 1, wherein the one or moreresources comprise one or more time slots.
 6. The method of claim 1,wherein the message further specifies a weight of the second node. 7.The method of claim 6, wherein the weight is associated with a degree ofdisadvantage of the second node.
 8. The method of claim 7, wherein thedegree of disadvantage is function of least one of a group consistingof: throughput of the second node, latency experienced by the secondnode, data rate of the second node and spectral efficiency of the secondnode.
 9. The method of claim 6, wherein the determination of thetransmission power comprises comparing the weight of the second node anda weight of the first node.
 10. The method of claim 1, wherein themessage further specifies a target interference level at the secondnode.
 11. The method of claim 10, wherein the determination of thetransmission power comprises selecting a transmission power based on thetarget interference level at the second node.
 12. The method of claim 1,wherein the message further specifies a target reduction of interferencelevel relative to a current interference level experienced by the secondnode.
 13. The method of claim 12, wherein the determination of thetransmission power comprises selecting a transmission power based on thetarget reduction of interference level at the second node.
 14. Themethod of claim 1, wherein the first node is an AT and the second nodeis an AP.
 15. The method of claim 1, wherein the first node is an AP andthe second node is an AT.
 16. The method of claim 1, wherein the messageis sent by the second node.
 17. The method of claim 1, wherein themessage is sent by a third node and further wherein the first and thirdnodes are AP and the second node is an AT.